42 Design and development of laboratory apparatus and instruments; design and development of scientific, optical, measuring apparatus and instruments; research and development with respect to measuring the physico-chemical properties of fluids; research and development with respect to measuring the physico-chemical properties of a particles mix; research and development with respect to the measurement and determination of the size distribution of a particles mix; design, development, installation and maintenance of computer software and applications for use by laboratory apparatus and instruments; design, development, installation and maintenance of computer software and applications to be implemented in measuring and determining the size distribution of a particles mix